Astrophysics (Index)About

light-year

(ly)
(distance that light travels in a year)

A light-year is the distance that light travels in a year. The count of light-years to some object under observation also represents how far into the past this view of the object represents, i.e., if a star is ten light years away, then when we see it, our view is of that star's appearance ten years ago. In the science of astronomy/astrophysics, the unit light-year is often used for communications to the public, but the unit parsec (pc) is generally used in scientific calculations and communication. Equivalences:


(distance,unit,astronomy)
Further reading:
https://en.wikipedia.org/wiki/Light-year

Referenced by pages:
Achernar
AD Leonis (AD Leo)
Algol (Beta Per)
Alpha Centauri (α Centauri)
Automated Planet Finder (APF)
Arcturus
astronomical quantities
astronomical unit (AU)
AzTEC-3
Barnard's Star
Beta Centauri
Beta Pictoris b (β Pic b)
Canis Major Dwarf Galaxy
Cassiopeia A
CHIPSat
Circinus Galaxy (ESO 97-G13)
Coma Supercluster
Comet Galaxy
Elias 2-27
Epsilon Eridani
Epsilon Indi (ε Indi)
ESO 137-001
51 Eridani b
51 Pegasi b (51 Peg b)
47 Tucanae (47 Tuc)
fuzzy dark matter (FDM)
G239-25
Great Attractor
Great Wall
GRO J1655-40
HD 189733 b
HD 209458 b
HD 80606 b
Hercules-Corona Borealis Great Wall (Her-CrB GW)
HL Tau
HR 8799
Hyades Cluster
Hydra-Centaurus Supercluster
IC 342
IRAS 13224-3809
J1407
K2-18b
Kapteyn's Star
Kepler-79
Lalande 21185
LHS 1140
LHS 3844 b
Local Interstellar Cloud (LIC)
Large Magellanic Cloud (LMC)
Local Bubble
Local Group (LG)
Luhman 16
Luyten 726-8
Crab Nebula (M1)
Messier 100 (M100)
Pinwheel Galaxy (M101)
Sombrero Galaxy (M104)
Messier 106 (M106)
Messier 15 (M15)
Andromeda (M31)
Triangulum Galaxy (M33)
Whirlpool Galaxy (M51a)
M64
Messier 74 (M74)
M82
Messier 84 (M84)
M87
Milky Way
NANOGrav
NGC 1600
NGC 253
NGC 2770
NGC 3201
NGC 3314
Spindle Galaxy (NGC 5866)
OB association
observable universe
Oort Cloud
Orion
parsec (pc)
Perseus-Pisces Supercluster
Pisces-Cetus Supercluster Complex
Procyon
Proxima b
Hulse-Taylor Binary (PSR B1913+16)
pulsar timing array (PTA)
Puppis A
quasar (QSO)
Radcliffe wave
redshift (z)
Rho Ophiuchi Cloud Complex
Rigel
Ross 154
Ross 248
Sagittarius Dwarf Irregular Galaxy (SagDIG)
Sagittarius Dwarf Elliptical Galaxy (Sgr dE)
Scholz's Star
Sculptor Wall
Sloan Great Wall (SGW)
Sirius
Small Magellanic Cloud (SMC)
SN 1987A (1987A)
SN 2014J
Sun
supercluster
survey depth
Teegarden's Star
3C 273
3C 279
3C 295
3C 48
TOI 700 d
TRAPPIST-1
TW Hydrae (TW Hya)
2M1207
Vega
Vela supernova remnant
void
WASP-43b
WISE 0855-0714 (W0855)
WISE 1506+7027
Wolf 359

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